This invention relates to hydrogen generators, and more particularly, to a cartridge-type hydrogen generator which relies at least partially on the process of anodic corrosion to produce hydrogen.
Hydrogen generators which produce quantities of hydrogen of relatively high purity have many uses. One such use is to provide hydrogen fuel to a fuel cell power generation system. Fuel cell systems, especially those used in remote locations, are equipped with integral fuel sources to operate the cell over a period of time. One approach for supplying hydrogen to the cell is by having a hydrogen generator located at the fuel cell to supply the needs of the cell. Such hydrogen generators are desirably demand responsive; that is, they produce hydrogen only when the fuel cell needs it. Demand responsive generators should be designed to require little or no hydrogen storage after the hydrogen is generated and before it is supplied to the fuel cell. This is beneficial from the safety standpoint.
One type of known hydrogen generator uses a gas generator cartridge. Hydrogen is produced by the reaction of water and a solid cartridge charge, such as a calcium hydride which reacts vigorously with water, to generate hydrogen gas and leave a solid residue in the form of a metal hydroxide. Hydrogen generators employing cartridges of this type normally employ a reservoir of water or provide a chamber into which water is supplied and brought into contact with the cartridge charge. When it is desired to generate hydrogen, one or more cartridges are placed in a reaction tank and then water is supplied to the reaction tank. As the water level rises, it comes into contact with and covers the cartridge. A liner in the cartridge becomes saturated with water and the water passes therethrough and into contact with the cartridge's charge. The water reacts exothermically with the particles to form calcium hydroxide and hydrogen gas.
In demand responsive hydrogen generators, there are several aspects of the hydrogen generation system which are of importance. The first is the ability to precisely control the hydrogen formation process; that is, the ability to start the process and stop the process substantially instantaneously. The generator, desirably, should not have a lag factor in providing hydrogen to the system that utilizes it, such as a fuel cell, which could jeopardize the continuous operation of the system. Similarly, the generator, desirably, should not have a lag factor in stopping the formation of hydrogen after the requirements of the system to which it is fed have been satisfied since the excess hydrogen would have to be bled off or placed in some sort of storage facility. Having to bleed off excess hydrogen would, of course, waste a portion of the hydrogen produced and make the generator somewhat inefficient. A second important consideration is the rate of hydrogen production during the generator's operation. The formation of hydrogen should be at a sufficiently high rate for the application intended. It is also desirable to have the generator employ an anodic material of high energy density, to have a high output of hydrogen for the volume and weight of the cartridge and a high degree of utilization of the reactants.
It is an object of the invention to provide a demand responsive hydrogen generator.
It is a further object of the invention to provide a hydrogen generator which can be turned on and off substantially instantaneously.
It is a further object of the invention to provide a hydrogen generator which has a high energy density and improves the rate of hydrogen formation relative to the amount of materials employed.
It is a further object of the invention to provide a replaceable cartridge-type hydrogen generator.
It is a further object of the invention to provide a compact hydrogen generator relative to the amount and rate of hydrogen generated thereby.